I'd rethink that 4 speed and consider an 8 speed. That was something I loved about that Charger, the 8 speed transmission was outstanding. They'll let you have a strong takeoff, keep you in the powerband longer when accelerating and still spin the engine slowly enough at highway speeds to get good mileage. Even the 6 speed the new Tahoe has feels like there's not enough gears and going back to the truck, not happy at all anymore with that transmission. It still works well, but after driving an 8 speed, a 4 speed just seems lame now.

I dunno, the GM 8 speed is rated for 650HP/635TQ, and that's before the aftermarket gets hold of it. The 4L85E is good for 450HP/450TQ stock. More power to the rear wheels due to less drivetrain loss, the potential for more power handling capability from the aftermarket, engine kept in the powerband longer, better mileage when cruising (in the Charger the 8 speed was worth about 3MPG over the old 5 speed), there's really not that much downside here aside from the extra install expense. You would have to put in some sort of paddle shifting system to access all the gears, and figure out the computer for it.

Gotcha. As much as you research these things I figured you knew, but I didn't know if you'd ever driven an 8 speed equipped vehicle. The trans is only good for about 0.2 in the quarter in the Charger, so there isn't that much of a power advantage, but the rear gearing on an 8spd is 3.08 vs 3.92 on the 5 speed. Mileage and drive feel is where the 8spd shines. I loved how my truck's trans ran before the Charger but now the drive feel is disappointing. The 6spd in the Tahoe makes for a better drive, but even it is less than I'd like. I couldn't justify 75G for a new Denali to get a 6.2 and an 8 speed though, when the 2015 I got was about 35K. 40K would buy a turbocharged LSX454 and an 8spd with money left over to paint, redo the interior and buy 20 years of fuel (not that I'm doing any of this! )

I was seriously turned off by the ZF 9 speed in my Aunts MOPAR product. It has a super wide ratio, but didn't seem to have the off idle torque and or the ability to pull 9th gear at any reasonable ie legal speed. It has a total ratio coverage of over 9.0:1, I think they got a little greedy on the 9th gear or high end of the ratios.
It had the 3.2 liter 6 IIRC.

And Speeder something that will interest you, that line of Cherokee had to have software revisions as it was discovered that hackers could infiltrate the vehicles systems and control some of them.

Wiki copy paste
Software hack[edit]

in July 2015, FCA issued a recall of 1.4 million vehicles after a software glitch was discovered which would allow hackers to wirelessly hijack vehicles and electronically control vital functions. [15] IT security researchers Charlie Miller and Chris Valasek hacked a 2014 Jeep Cherokee and gained access to the car over the Internet, which allowed them to control the vehicle's radio, A/C, and windshield wipers, as well as the Cherokee's steering, brakes and transmission.[15] Chrysler published a patch that car owners can download and install via a USB stick, or have a car dealer install for them.[15]

The last Vette I drove was an GEN 5 SBC LT1 car with the 7 speed TR6070, during city driving I will admit that I got lost in the gears. That car needs a set of 4.56 rear gears, for anything remotely useable in the city. I've always hated the Vettes gearing, even from 1988-89 when the ZF-6 speed replaced the Doug Nash 4+3 transmissions. Low 3:1 rear gears with a mid 2-3:1 1st gear ratio just made me work too much from a stop. And that was the time of the TPI L98 350 which was no slouch in the torque department.
But these new GEN 5 SBCs are in another league. They have 11.0-11.5 compression ratios(depending on displacement) right off the bat along with the Direct Injection/ piston/combustion chamber/cylinder head designs just keep taking leaps and bounds forward.
Even the supercharged GEN 5 SBC rpo LT4 starts with a 10.0:1 compression ratio.that uses the smaller, but spun faster (20,000rpm)1.7 liter Twin Vorticies Supercharger(TVS) to make 10.4psi of boost to make its 650hp. he previous GEN 4 SBC, the LS9 required 10.5psi of boost from its larger 2.3 liter TVS blower, spun at a slower 17,400.to make its 638hp.

Remember when the 1992-1997 GEN II LT1's compression ratio of 10.4:1 required all that fancy reverse cooling that ran coolant from the heads to the block, rather than the conventional coolant flowing from the block to the heads. Then for MY 1996, to say goodbye to the GEN II SBC Powertrain came up with the LT4 engines which was rated at 330 net hp@5800rpm/340lb/ft torque@4500rpm. It had the specific LT4 roller cam, 1.6:1 full roller tip and trunnion rocker arms(the ONLY GM V8 to ever use BOTH the rollerized tips and fulcrums, til 1996 and since 1996-only the roller fulcrum has been used since-maybe the 2 recalls related to the rocker arms put a foul taste in GMs mouths?), revised LT4 specific 195cc intake runner volume/raised runner cylinder heads featuring 54.4cc combustion chamber volumes, sodium filled hollow exhaust valves with the larger 2.00"/1.55" sized valves which are still used IIRC on the Fastburn 210cc heads,
specifically machined nodular cast iron crankshaft for LT4- LT1 p/n=12556307 LT4 p/n=12551485
Blurb on special machining operations on the LT4 cranks from GrandSport Registry
"The crank itself was improved via something called undercutting and rolling. Undercutting is the machining of a groove into the corner of a journal. Though this would seem to weaken the crank at that point, it actually makes it stronger where tensile stress is most likely to cause sudden failure. Rolling the undercut introduces compressive stress to the area. This makes it more durable, because potentially catastrophic tensile stress generated during high RPM operation must first overcome the compressive stress before that area of the crank is subjected to tension. Undercutting, a groove cut into the corner of a journal, looks counterintuitive, but makes a crankshaft stronger where tensile stress is most likely to cause failure. By undercutting and then rolling it, compressive stress is introduced. Tensile stress during high-speed operation first has to overcome the compressive stress before there's any tension on the joint. And as tensile stress is what breaks crankshafts, undercutting and rolling make the crankshaft stronger."

LT1 intake runner 170cc/LT4 intake runner 195cc

LT1=A LT4=B exhaust

Injectors went from 3.0 grams/second about 24lb/hour to 3.5 grams/second or about 28 lbs/hour

The hugely overpriced LT4 intake manifold, which is red use p/n=12550630 while the LT1 intake uses 12552137. The only difference is that due to the raised intake runner of the LT4 195cc head, there is slightly more aluminum cast around the edges intake so that it holds the gasket securely. The LT4 intakes isn't some holy grail of GEN 2 hp, it doesn't deserve the hoopla that more rare stock/OEM intake manifolds enjoy. One example would be the SLP designed T-Ram for the LB9/L98 TPI engines. Now that is an intake manifold that actually does allow for marked increases in performance.

LT4 also used specific springs that were actually drawn from a spring wire that was ovate or oval in shape. In theory you could compress a spring made of oval wire further before the coils themselves would touch each other. Many people scoff at this because they are literally visualizing the valve springs being compressed like they would when you are testing valve springs with a spring tester. The springs are compressed nice and slow and evenly with the spring machine, then they are released nicely when the operator allows the handle to release the spring pressure. Well in an engine, esp. a performance engine with camshafts that have "steps" rather than "ramps" to actuate the lifters, the valve springs often do weird things. They starts to bounce and oscillate at high rpm, and sometimes at lower rpms that I used to think that springs would have an issue, but they did. That few extra thousands of an inch that is gained in between each coil of a valve spring when they are drawn of ovalled wire, could make or break that spring from wearing out and/or breaking.
Cloyes did a custom front timing gear and timing chain assembly. The chain was a super high quality true roller design that you can get anymore. It was used for a while on some of the crate engines that GMPP did for a few years after the LT4.

from GrandSport Registry site
"Stock LT1 has powdered metal butt link chain drive for the camshaft and water Pump. LT4 has smaller but stronger steel roller chain. Although it seems that the new chain and sprockets would reduce mass, The cam sprocket was left solid, rather than webbed, specifically for additional mass. Increased inertia in the system reduces the tendency for cam torsion. "

the GEN II LT4 also used special nodular iron main bearing supports that are much stronger than the conventional LT1 supports. And just like ALL the aluminum LT1/4 blocks that were destined for use in Corvettes, it got 4 bolts per main, while the F-body(Firebird/Camaro), B-body Caprice/ImpalaSS and D-body Cadillac Fleetwood(94-96 iron heads like Caprice) all got the 2 bolt mains with normal iron supports.

Just wait until MY2018/19 when the new LT5 DOHC V8 debuts in the Vette. Lets just say that the torque and power peaks will be at rpm levels that will make the L37 Northstar V8 with its 6000-6300rpm 300-320hp power peak and 6800rpm redline, and the 90-92 LT5 with its 375hp power peak at 6000rpm and the 1993-1995 405hp power peak of 5800rpm and the 7200rpm fuel shutoff/redline of 7200rpm, look like slouches. The new LT5 wont e supercharged, and if you buy a car based on power numbers, it probably wont appeal to you, but it will be a rev happy engine that will make a lot of us smile. A 7950rpm torque peak may or may not be advertised for this 6.2liter/376cid DOHC engine. Makes me wonder where the power peak will be? Throwing a shift at 8500rpm has a certain attraction for some I'm sure.

Sorry about the novel, but nothing gets be charged like talking about SBC engines. With all the engine advancements, it only makes sense that the transmissions develop as well. Still waiting for that real world CVT though.

Just as I predicted. We aren't far off from all cars going to 88MPH and executing a hard left turn (or hard right in nations where they drive on the left side) on, say, the anniversary of Back to the Future, or 100MPH and hard turn on Guy Fawkes' birthday, something along those lines.

I can see where a manual high-gear trans would be hard to work in the real world, but the automatics for rear wheel drive work really well. They are nearly seamless under light load conditions and when you nail it they go straight to the gear they need to be in. They don't require, say, going from 8th gear to 3rd gear to cycle through 876543, they go from 8 to 3 directly. With the computer doing the shifting work for you, you really just need to tweak the software so that the computer will go to the gear you want it to go to. On that Charger I had, Chrysler already had the 8 speed pretty much going where I'd have put it already so minor tweaking was needed. They hit a solid foul ball on the downshifts while stopping though, the car's downshifts were noticeable when coming to a stop. It was like you were trying to stop by downshifting instead of using the brake, you could feel them. The car felt like it was fighting you to stop as well, so it was very hard to get the car to stop smoothly unless you shifted to neutral first. If I'd have been able to keep that car, I definitely would have worked on getting it reprogrammed as soon as the warranty expired.

Funny, I don't miss that car at all. Low 13s in the quarter, almost 30MPG when cruising on the highway, and I don't miss it. I just wish I could have put the transmission in my Tahoe.

Sat Sep 02, 2017 8:59 am

1999 Tahoe 4x4

Joined: 15 Dec 2007
Posts: 751
Location: Torrance, CA

On the new engines you can't change the lifters any more without removing the heads.

I am patiently waiting for GMPP to offer a standalone transmission controller that interfaces with a gen 3 ECM for the newer transmissions. I would love to do an LS swap and be able to use a 8 speed transmission. The problem with the newer vehicles that use those 6 & 8 speeds is that many vital functions like cruise control and A/C request gauge signals, etc are on the data bus and routed through the body control module. I doubt that GM will ever offer controllers that interface with earlier ECM's though. Right now the only option is to use all the electronics from the donor vehicle including a BCM....

Thu Sep 07, 2017 12:32 pm

DomingoSpear

Joined: 17 Jan 2019
Posts: 1

GM has used five different blocks for the Gen III family. There are iron blocks for the 4.8L/5.3L and 6.0L along with aluminum blocks for the 5.3L, 5.7L and 6.0L.